1. Technical Field
The present invention generally relates to an electronic device, and more particularly, to a semiconductor memory device and a method of programming the same.
2. Related Art
Existing Hard Disk Drives that rotate a physical disk are relatively slower, heavier, and larger, than semiconductor memory devices. Thus, the use of semiconductor memory devices has increased.
A semiconductor memory device is a memory device implemented by using a semiconductor, such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), an indium phosphide (InP). Semiconductor memory devices are generally classified into volatile memory devices and nonvolatile memory devices.
Stored data dissipates from a volatile memory device when a power supply is cut from the device. The volatile memory device includes a Static RAM (SRAM), a Dynamic RAM (DRAM), a Synchronous DRAM (SDRAM), and the like. Stored data is maintained within the nonvolatile memory device even though a power supply is cut from the device. The nonvolatile memory device includes a Read Only Memory (ROM), a Programmable ROM (PROM), an Electrically Programmable ROM (EPROM), an Electrically Erasable and Programmable ROM (EEPROM), a flash memory, a Phase-change RAM (PRAM), a Magnetic RAM (MRAM), a Resistive RAM (RRAM), a Ferroelectric RAM (FRAM), and the like. The flash memory is generally divided into a NOR type and a NAND type.
Recently, research to increase the number of bits programmed in one memory cell has been conducted. However, when the number of bits programmed in one memory cell is increased, various levels of voltages need to be supplied in order to verify a program progress state. Accordingly, the time needed for the programming may be increased.